1. Field of the Invention
The present invention is directed to a slot cutting apparatus and method, and in particular to a slot cutting apparatus and method for cutting slots to form recesses across joints in pavement to repair faults and/or reinforce the pavement.
2. Prior Art
Slots are formed in pavement joints to define sides of a recess into which reinforcement devices are inserted to attach the pavement sections on either side of the joint. Such pavement joint reinforcement devices are well known and have been widely used for several years. Premature fatigue at the contraction joints is known as faulting and is repaired through load transfer restoration to improve the pavement strength across the joint and to slow down future fault development. A pair of aligned slots are cut in the pavement and the material between the slots is removed to form a recess. In some cases, reinforcement across the joint never existed, while in others, replacement is necessary. The dowels anchor to both pavement sections and improve load transfer across the joint. Dowels are conventionally placed in the recesses formed in both portions of the pavement and backfill material is placed in the recess to anchor the dowels. The support dowels and their effectiveness are improved by a strong bond between the reinforcement device in the recess and the pavement walls of the recess.
As several recesses are formed along each joint to receive a corresponding number of reinforcement devices, and as there are large numbers of joints along roads, the process for cutting slots is a time consuming one. The slot cutting process typically involves diamond impregnated blades cutting pairs of slots forming recess sidewalls with a pair of aligned spaced apart blades. The material between the two cuts is removed to form a recess. Further challenges arise when attempting to align the cuts and provide a clean cut. Where the surface of the road is not level, the blades are often subject to lateral pressure as the cutting machine is moved forth and back causing wear to blades, bearings and other components.
In an effort, to overcome this problem, a cutting machine has been developed that locks the frame with only its cutting head moving relative to the frame. Although this may overcome some of the lateral pressure problems, it has several shortcomings. By using only the cutting head rather than the entire vehicle, the mass moving back and forth and the pressure applied to the pavement is relatively small. The momentum and mass of the cutting machine is not fully used as an advantage. A cutting apparatus and method that eliminates side pressure during cutting, yet uses the mass of the cutting device, rather than just a cutting assembly, would improve slot quality and prolong equipment life.
It can be seen then that a new and improved cutting apparatus and method is needed for cutting slots and to repair and replace reinforcement devices across contraction joints. Such an apparatus and method should provide for proper alignment of slots at both sides of the recesses and for cutting without damaging the bearings or the saw blades. Such an apparatus and method should also provide for using the full mass and momentum of a cutting vehicle to make the cuts, rather than just the mass and momentum of a cutting blade assembly. Slots of varying lengths and depths should be possible and should be made while maintaining the slots in alignment with one another. The present invention addresses these as well as other problems associated machines and methods for forming slots across pavement joints.